The present invention relates to a device for conveying electrodes used in the electrolytic refining or electrowinning of metals from one station to another, in which device the number of movable parts and mechanisms is limited, and the spacing of the electrodes is maintained essentially the same.
In electrolytic plants used for producing metals, such as copper, nickel and zinc, there are processed remarkable amounts of electrodes, anodes and cathodes. Owing to the large quantities to be processed, the processing is mainly carried out with machines, where an important function is to convey the electrodes from one working step to another.
Traditionally, chain and walking beam conveyors are used for conveying electrodes. However, in this type of conveyors there arise problems that are partly caused by the electrolytic conditions and partly to the structural arrangements of the conveyors. Problems caused by the electrolytic conditions are generally connected to mechanical wearing due to impurities in the electrodes, and to corrosion due to the corroding effect of the electrolyte. Conveyor arrangements are normally difficult to protect against these conditions.
A common problem with chain conveyors is the stretching of the chain, which is further enhanced by the impurities and corrosion typical of electrolytic processes. This is a particularly remarkable problem in electrolytic machines, because the electrodes should, in each processing station along the conveyor line, be brought to precisely the correct position, which can only be done with a conveyor where the spacing between the electrodes always remains exactly right.
As for the structural arrangements of walking beam conveyors, there is generally used a structure where the element conveying electrodes, i.e. the walking beam, both rises up and performs a controlled horizontal shifting motion prior to descending and returning to the initial position. The lifting step, where the walking beam raises the electrodes to be conveyed so that they are supported by the walking beam, mustxe2x80x94for functional reasons of the mechanismxe2x80x94be performed exactly in the same rhythm along the whole length of the walking beam, which makes the mechanism, particularly in long conveyors, heavy and complicated.
For all the above mentioned reasons, known conveyor arrangements are generally expensive, but still wear relatively rapidly and require a lot of maintenance.
The object of the present invention is to alleviate the drawbacks of the prior art and to achieve an improved device for conveying electrodes, used in the electrolytic refining or electrowinning of metals in an electrolytic plant, from one station to another, particularly when the electrodes are conveyed in the length-wise direction, i.e. in an essentially perpendicular direction with respect to the line connecting the electrode support points. The essential novel features of the invention are apparent from the appended claims.
According to the invention, in an electrode conveyor device to be used for electrolytic refining or electrowinning in an electrolytic plant, the horizontal conveying motion proper, and the lifting motion required by the walking beam principle are assigned for separate members. For performing the conveying motion, the conveyor comprises at least one conveyor member, and for the lifting motion, at least one lift member. Advantageously the conveyor device according to the invention comprises two conveyor members and respectively two lift members. Moreover, the conveyor device according to the invention usually has a modular structure, in which case one module is formed by two conveyor members and respectively by two lift members. When employing a pair of conveyor members and respectively a pair of lift members, the electrode to be conveyed is advantageously supported at both ends of the supporting structures of the electrode.
In a conveyor device according to the invention, the conveyor member is formed of an essentially rail-like structure, which is advantageously installed underneath the electrode supporting structures, such as cathode hangers and anode support lugs, so that the conveyor member is movable back and forth, essentially for the length of the electrode conveying step only, in an essentially horizontal direction.
In a conveyor device according to the invention, the lift member is formed of a lift plate, which also is installed advantageously underneath the electrode supporting structures, such as cathode hangers and anode support lugs, so that the lift member is movable back and forth essentially for the length caused by a possible indentation of the conveyor member and the lift member only. The lift member is essentially movable in the vertical direction only, when said lift member is supported so that the motion as such is not linear.
Advantageously the conveyor device according to the invention is formed of one or several modules, each module advantageously comprising a pair of conveyor members and a pair of lift members supported against the module housing structure. Moreover, in between the module housing structure and the essentially horizontally movable conveyor members on one hand, and the essentially vertically movable lift members on the other hand, in the module there are installed support members creating the desired motion, such as roller support and control, slide rail support and control, or a combination of these. The back and forth motion of the conveyor and lift members is advantageously generated by hydraulic cylinders, but other types of drive elements can also be used for creating the motion, such as pneumatic or electric drive elements.
The operation of a conveyor device according to the invention is based on the following steps:
1) the lift member lowers the electrode down, to rest supported by the conveyor member,
2) the conveyor member conveys the electrode for the length of a desired horizontal step,
3) the lift member lifts the electrode up from the support of the conveyor member, and
4) the conveyor member returns, without the load, to the initial position in order to start a new cycle.
In the conveyor member according to the invention, the essentially horizontal conveying motion proper and the lifting motion required by the walking beam principle are performed by separate members, and therefore the structure of the conveyor device allows for the conveyor members to move separately at different times or in a different rhythm, the lift members to move separately at different times or in a different rhythm and even the ends of each lift member to move separately at different times or in a different rhythm, in case in between the above described operational steps, it is observed that all motions of the preceding step are performed. In particular the fact that the operation of the conveyor device according to the invention allows for the lift members to move separately at different times or in a different rhythm and even the ends of each lift member to move separately at different times or in a different rhythm makes the module of the conveyor device according to the invention essentially simpler than the traditional walking beam conveyors.
The modular structure of the conveyor device according to the invention is made particularly advantageous by the fact that because the weight of the electrodes, cathodes or anodes, in each electrode type is essentially constant, in the module essentially only the housing width and height are chosen according to the measures of the electrode in question. In case a single module structure becomes essentially long, said module structure can be combined of several successive modules. The modules can be placed in succession essentially without mechanical coupling. In the case of more than one module, the modules can advantageously be controlled in the same fashion as one single module, i.e. for example all actuators of the lift members and all actuators of the conveyor members can be mutually connected to be under one and the same control. When necessary, also the conveyor members of successive modules can be mechanically connected. In similar fashion, it may be advantageous, from the point of view of the installation and use of the conveyor device, that at least the housings of successive modules are mechanically connected, for instance by means of a bolted joint.
When using the conveyor device according to the invention, the spacing of the electrodes always remains essentially constant. Because the horizontal and vertical motions are separated for their specific members, the actuators as such are simple, and mechanical synchronisation between the motions is not necessary. Consequently, the structure is economical in manufacturing expenses, and the maintenance needed by the structure is minimal. Also the number of movable parts and mechanisms in the conveyor device is essentially small, in which case the structure becomes strong and has a long working life.